Ahead of her 'Jimmy Kimmel Live!' showing, Katy Perry took a page out of Taylor Swift's style playbook in a 'fit similar to the 'TTPD' singer's Super Bowl look.

Katy Perry could really hear her fans 'Roar' last night ... probably screaming out in horrible pain -- 'cause one of them ...

Katy Perry left American Idol behind, and there was speculation that things were not good between her and her co-stars behind ...